In its recent judgments on preliminary objections in the cases of Alleged Violations of Sovereign Rights and Maritime Spaces in the Caribbean Sea (Nicaragua v Colombia) and the Question of the Delimitation of the Continental Shelf between Nicaragua and Colombia beyond 200 nautical miles from the Nicaraguan Coast (Nicaragua v Colombia), the International Court of Justice (“ICJ”) had to deal with arguments based on a contrario interpretation. This form of interpretation, according to which “the fact that a provision expressly provides for one category of situations is said to justify the inference that other comparable categories
are excluded”, has been addressed several times in the jurisprudence of the Court and its predecessor, the Permanent Court of International Justice (“PCIJ”). Yet, despite assertions that the maxim of interpretation would “find a place in the logic of the nursery”, there remain fundamental questions about both its character and its operation. This article addresses two of those questions: how has a contrario interpretation been used in the practice of the PCIJ and ICJ, and how might we explain the importance attributed to it?
